US President Barack Obama hosts a private dinner for Chinese President Xi Jinping at Blair House in Washington DC, September 24, 2015. [Photo by Lan Hongguang/Xinhua]

President Xi Jinping and President Barack Obama held a three-hour private dinner Thursday night, investing more time in building personal ties.

The private dinner, scheduled for two hours, extended to about three hours, with people around the event saying the two leaders explored many issues.

The two presidents walked shoulder to shoulder through the Pennsylvania Avenue before arriving at the Blair House, reminding audience of their talks during the past two years.

State Councilor Yang Jiechi, Foreign Minister Wang Yi, and Xi's presidential office head and chief aid Ding Xuexiang joined the dinner.

On the US side, Secretary of State John Kerry and National Security Adviser Susan Rice were on hand for the informal dinner.

Fan Jishe, a US studies researcher at the Chinese Academy of Social Sciences, said the kind of private, informal talk between Xi and Obama will help nurture personal trust between the two nations' leaders and give them a chance to exchange visions on their country's strategic development, which has been a key concern for many people.

"We don't usually say this, but in the past, the top leaders' meetings were much more formal and sometimes ceremonial, during which personal relationships were not easy to be established," Fan said.

"The current small-scale and face-to-face meetings allow the two leaders to talk about matters frankly and sincerely, especially regarding some topics that are not likely to be raised during formal political meetings," Fan added.

Fan Jishe, a US studies researcher at the Chinese Academy of Social Sciences, said the kind of private, informal talk between Xi and Obama will help nurture personal trust between the two nations' leaders and give them a chance to exchange visions on their country's strategic development, which has been a key concern for many people.

"We don't usually say this, but in the past, the top leaders' meetings were much more formal and sometimes ceremonial, during which personal relationships were not easy to be established," Fan said.

"The current small-scale and face-to-face meetings allow the two leaders to talk about matters frankly and sincerely, especially regarding some topics that are not likely to be raised during formal political meetings," Fan added.